OpenFields

Investigation to increase understanding of the mechanisms and kinetics of bacteriophages/host interactions at low host concentrations.

Year of Publication2009

If bacteriophages (phages) are to be used to control foodborne pathogens it is necessary to understand both the mechanisms and kinetics of phage/host interactions at low host concentrations. To explore these questions phages infecting Salmonella and Campylobacter were incubated with host cells under conditions which did not allow them to replicate, and equations fitted to the inactivation data to produce contour maps of inactivation. The data were also analysed with respect to kinetics elucidated in work published elsewhere. In addition, we determined whether UV-inactivated phages could be used to control pathogens present in liquid foods at low concentrations using phage T4 and Escherichia coli as a model system. Inactivation of Salmonella by phages was independent of the host concentration but, for Campylobacter, there appeared to be an interaction of both phage and host concentrations. The data supported the need to determine MOIactual (vs MOIinput) to enable the prediction of the proportion of host cells killed. Viable and UV-treated E. coli phages behaved in a predictable manner and the concentration of UV-treated phages required to inactivate the host in a manner comparable to viable phages was 15-30 times greater. The data obtained were largely consistent with prior work indicating that, at low host cell concentrations, the proportion of cells killed is independent of the host cell concentration. Biocontrol of pathogens present at low concentrations in liquid foods is achievable given a sufficiently high concentration of phages, and it is possible to use UV-inactivated phages to produce the same effect.